JP7042198B2 - Embankment structure, embankment structure construction method and embankment structure repair method - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act February 20, 2018 Announced in "45th Japan Society of Civil Engineers Kanto Branch Technical Research Presentation Summary" published by Japan Society of Civil Engineers Kanto Branch

The present invention relates to an embankment structure in which an inclined surface is formed, a method for constructing the embankment structure, and a method for repairing the embankment structure.

The embankment on which the slope (slope) is formed is constructed for roads, railways, river embankments, etc., but if the inside of the embankment is saturated by seepage water due to rainfall, it becomes unstable and there is a risk of collapse. In order to increase the number, various countermeasures will be taken.

On the other hand, as a property of soil, there is a "capillary barrier" in which a water retention area is created in the fine-grained soil in the upper layer due to the difference in permeability between the fine-grained soil in the upper layer and the coarse-grained soil in the lower layer in an unsaturated state. It is known and has been used for burial mounds and waste disposal sites in ancient times.

Patent Document 1 discloses a technique of driving a drainage pipe from an inclined surface toward the inside of the embankment as a measure for drainage of the existing embankment. This drainage pipe is provided with a large number of slits and water intake openings on the peripheral wall of the pipe, and when water in the surrounding embankment is taken in, drainage is performed from the discharge port exposed on the inclined surface. ing.

Japanese Unexamined Patent Publication No. 2016-30992

However, when a large amount of water permeates the embankment in a short time due to heavy rain, etc., it is necessary to efficiently drain the water from the embankment. Only a limited range of water can be drained, and there is a risk that slope collapse cannot be prevented.

Therefore, an object of the present invention is to provide an embankment structure, a method for constructing the embankment structure, and a method for repairing the embankment structure, which can efficiently drain water inside the embankment.

In order to achieve the above object, the filling structure of the present invention is a filling structure in which an inclined surface is formed, and is formed on a capillary barrier layer formed inside the filling with a predetermined thickness and on the capillary barrier layer. The provided water permeability in an unsaturated state is higher than that of the capillary barrier layer, and the water retention area is extended near the boundary between the capillary barrier layer and the water retention area to take in water that has permeated the water retention area and to take in the inclined surface. The capillary barrier layer, the drainage path portion, and the drainage group portion having the water retention area as one set are provided with a drainage path portion provided with a discharge port, and a plurality of drainage group sections are spaced apart from each other in the height direction of the inclined surface. It is characterized by being provided.

Here, the drainage assembly portion is continuously provided in the width direction of the inclined surface, and the drainage route portion may be provided at intervals in the width direction. Further, the drainage assembly portion may be configured to be provided at intervals in the width direction of the inclined surface.

Further, in the capillary barrier layer, the coarse-grained soil portion formed by the coarse-grained soil and the fine-grained soil portion formed by the soil particles having a finer particle size than the coarse-grained soil are alternately arranged. The structure can be extended substantially horizontally from the inclined surface toward the inside of the embankment.

Further, the capillary barrier layer can be 20 cm-50 cm. Further, the capillary barrier layer can be configured to be formed of coarse-grained soil having a particle size of 20 mm to 150 mm. The capillary barrier layer can have a structure that is substantially horizontally extended from the inclined surface toward the inside of the embankment to a length of 2 m to 3 m.

Further, the invention of the method for constructing a filling structure is a method for constructing a filling structure in which an inclined surface is formed, in which a step of laminating the filling material and a coarse-grained soil or a drainage material are laid inside the filling with a predetermined thickness. The step of providing the capillary barrier layer by the above step, the step of extending the drainage path portion on the capillary barrier layer so that the discharge port is provided on the inclined surface, and the step of extending the drainage path portion on the capillary barrier layer in an unsaturated state. The step of providing a water-retaining area having a higher water permeability than the capillary barrier layer and the drainage group portion having the capillary barrier layer, the drainage path portion, and the water-retaining area as one set are repeatedly provided between the layer made of the filling material. It is characterized by having a process of drainage.

Further, the invention of the method for repairing the filling structure is a method for repairing the filling structure in which the existing inclined surface is formed, and the step of partially excavating the inclined surface toward the inside of the filling and the excavated bottom surface. A step of providing a capillary barrier layer by laying coarse-grained soil or a drainage material with a predetermined thickness, and a step of extending a drainage path portion on the capillary barrier layer so that a discharge port is provided on the inclined surface. It is characterized by comprising a step of providing a water retention area having a water permeability higher than that of the capillary barrier layer in an unsaturated state on the capillary barrier layer and the drainage path portion.

The embankment structure of the present invention configured in this way has a capillary barrier layer that extends toward the inside of the embankment, a water retention area that is provided on the capillary barrier layer in an unsaturated state and has a higher water permeability than the capillary barrier layer, and a capillary barrier. It is provided with a drainage path portion that is extended near the boundary between the layer and the water retention area and has a discharge port on an inclined surface. A plurality of drainage sets including the capillary barrier layer, the drainage path section, and the water retention area are provided at intervals in the height direction of the inclined surface.

When water permeates such an embankment structure, a capillary barrier is developed near the boundary between the capillary barrier layer and the water retention area of each drainage group, and the saturation level is locally increased, and the drainage arranged in the vicinity thereof. Water can be drained quickly from the route. Therefore, the water inside the embankment can be drained efficiently.

If it is a new construction, such an embankment structure can be completed by sequentially providing a structure as a drainage assembly portion in the middle of the process of laminating the embankment material. In addition, when repairing an existing embankment, it is possible to provide a structure that serves as a drainage group by partially excavating the inclined surface toward the inside of the embankment.

It is explanatory drawing which showed the structure of the embankment structure of embodiment of this invention. It is sectional drawing explaining the whole composition of the embankment. It is a front view explaining the structure of the embankment structure in which the drainage group part is continuously provided in the width direction of the inclined surface. It is a front view explaining the structure of the embankment structure in which the drainage group part is provided at intervals in the width direction of the inclined surface. It is a process diagram explaining the process of the method of constructing the embankment structure of the embodiment of this invention in the case of newly constructing an embankment. It is a process diagram explaining the process of the method of repairing the embankment structure of the embodiment of this invention in the case of repairing an existing embankment. It is sectional drawing which explains the example which the capillary barrier layer is formed by arranging a coarse grain soil part and an embankment material part alternately.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of the embankment structure of the present embodiment, and FIG. 2 is a cross-sectional view illustrating the overall configuration of the embankment 1 provided with the embankment structure. First, the configuration of the embankment 1 will be described with reference to FIG.

Such embankment 1 is constructed for roads, railroads, river embankments, and the like. Further, the embankment 1 is formed in a substantially trapezoidal shape in cross section, for example, having inclined surfaces 11 on both side surfaces. The embankment 1 in FIG. 2 has an embankment structure in which an inclined surface 11 having a 1: 1.5 gradient is formed. FIG. 2 shows one side of a cross section of an embankment 1 provided with a small step serving as a middle step portion 13 in the middle between the top end 12 and the buttock portion 14.

In such an embankment 1, drainage layers 15A and 15B are usually provided on the bottom of the middle section 13 and the bottom of the fill, respectively. The drainage layers 15A and 15B are formed of crushed stone, a filter material, or the like, and are extended toward the inside of the embankment.

Such drainage layers 15A and 15B are usually provided to prevent a large arc slip including the inclined surface 11. When there is rainfall, the inside of the embankment 1 is saturated from the lower part by the seepage water due to the rainfall, and the drainage layer 15B drains from the saturated portion.

Therefore, the drainage layer 15A in the middle portion 13 of the embankment 1 will not function unless the seepage water level rises and the inside of the embankment near the drainage layer 15A is saturated. Therefore, there is a possibility that it is not possible to prevent the surface layer collapse or the slope collapse near the inclined surface 11 in the event of torrential rain or the like only by providing these drainage layers 15A and 15B.

Therefore, in the embankment structure of the present embodiment, a plurality of drainage assembly portions 2, ... Are provided at intervals in the height direction of the inclined surface 11. As shown in FIG. 1, the drainage group 2 includes a capillary barrier layer 3 extending substantially horizontally from the inclined surface 11 toward the inside of the embankment, a water retention area 5 provided in contact with the upper surface thereof, and a capillary barrier layer. It is mainly composed of a perforated drainage pipe 4 as a drainage path portion extending near the boundary between the water holding area 5 and the water retention area 5.

The capillary barrier layer 3 is a coarse-grained soil layer formed of coarse-grained soil stretched to have a predetermined thickness D and a predetermined length L. Here, gravel material having a particle size of about 20 mm to 150 mm can be used for the coarse-grained soil. For this coarse-grained soil, either single-grain crushed stone or grain-adjusted crushed stone can be used.

The thickness D of the capillary barrier layer 3 can be set to 20 cm-50 cm, preferably 30 cm. Further, the length L extending from the inclined surface 11 of the capillary barrier layer 3 toward the inside of the embankment can be set to 2 m − 3 m.

The water retention area 5 is formed of fine-grained soil or the like, which is soil particles having a finer particle size than coarse-grained soil. Normally, the embankment material constituting the embankment 1 is soil particles having a finer particle size than the coarse-grained soil, so that the embankment material can also form the water retention area 5. In short, since the water holding area 5 and the surrounding material may be the same, the range that can be assumed to be the water holding area 5 is conceptually illustrated by the alternate long and short dash line.

On the other hand, the perforated drainage pipe 4 is a pipe material in which a large number of holes are perforated in the peripheral wall of the pipe so as to serve as a water collecting portion. The shape of the hole may be any form such as a slit having a rectangular shape in a plan view, a hole having a circular shape or an elliptical shape, or the like. Further, the structure may be such that a partial opening is provided in the upper half of the pipe peripheral wall and the opening is covered with a net material or a sheet-shaped filter material. For such a perforated drainage pipe 4, a steel pipe or a vinyl chloride pipe having a pipe diameter of, for example, about 60 mm to 100 mm, preferably about 75 mm can be used.

The perforated drainage pipe 4 having such a water collecting function can take in the water that has permeated into the water retention area 5, and also discharge the water taken into the pipe to the outside of the embankment from the discharge port 41 exposed on the inclined surface 11. Can be done.

Then, in the vicinity of the boundary between the capillary barrier layer 3 and the water retention area 5, a water retention area C in which more water is retained than in other areas is formed due to the development of the capillary barrier. Here, the "capillary barrier" is the water retention in an unsaturated state generated between the fine-grained soil in the upper layer and the coarse-grained soil in the lower layer, and has the property of retaining water in finer soil particles. Say that.

The "capillary barrier" is caused by the difference in permeability in the unsaturated state. Therefore, as described above, the upper layer is a water retention area 5 made of fine-grained soil, and the lower layer is a capillary barrier layer 3 made of coarse-grained soil. A barrier can be expressed. Here, in the case of saturated ground without air, the water permeability of the fine-grained soil is lower than that of the coarse-grained soil. On the other hand, in the unsaturated state where air is present in the gaps between the soil particles, the fine-grained soil has higher water permeability than the coarse-grained soil due to the difference in unsaturated infiltration characteristics. It can be said that the phenomenon caused by such characteristics is the "capillary barrier".

On the other hand, even when the upper layer is composed of fine-grained soil and the lower layer is composed of a drainage drain or the like, the water permeability in the unsaturated state is higher in the upper layer, and a capillary barrier can be developed.

Then, by arranging the catchment portion of the perforated drainage pipe 4 in the water retention area 5 where the water retention area C appears, even if the precipitation R falling on the inclined surface 11 permeates the inside of the filling, the water retention area 5 is efficiently used. It can be collected and quickly discharged from the discharge port 41 of the perforated drain pipe 4.

FIG. 3 shows the structure of an embankment structure in which the drainage group 2 is continuously provided in the width direction of the inclined surface 11. That is, the capillary barrier layer 3 of the drainage group 2 is provided as one layer near the inclined surface 11 of the embankment 1. Since the region in contact with the upper surface of the capillary barrier layer 3 is the water retention area 5, the water retention area 5 is also continuously formed in the width direction of the inclined surface 11.

On the other hand, the perforated drainage pipes 4 are discretely provided at intervals B1 in the width direction of the inclined surface 11. Since the area around the perforated drainage pipe 4 is the catchment area, the permeated water can be maintained by arranging the catchment areas to overlap or touch between the perforated drainage pipes 4 and 4 adjacent to each other in the width direction. It will be possible to collect and drain water from the entire area of water area 5.

FIG. 4 shows the structure of an embankment structure in which the drainage group 2A is provided at intervals in the width direction of the inclined surface 11. That is, the capillary barrier layer 3A of the drainage group 2A is discretely provided near the inclined surface 11 of the embankment 1. Since the region in contact with the upper surface of the capillary barrier layer 3A is the water retention area 5A, the water retention area 5A is also formed discretely in the width direction of the inclined surface 11.

In short, the capillary barrier layer 3A and the water retention area 5A are provided according to the arrangement interval of the perforated drainage pipe 4. That is, the configuration may be such that the periphery around the perforated drainage pipe 4 is the water retention area C.

Here, the width of the inclined surface 11 of the capillary barrier layer 3A in the width direction is B2, and the distance between the capillary barrier layers 3A and 3A is B3. Further, it is preferable that the arrangement of the upper and lower capillary barrier layers 3A, ... Is shifted in the width direction of the inclined surface 11 such as in a staggered arrangement. The width B2 of the capillary barrier layer 3A in the width direction and the distance B3 between the capillary barrier layers 3A and 3A can be arbitrarily set by design.

Next, a method of constructing and repairing the embankment structure of the present embodiment will be described with reference to FIGS. 5 and 6. First, a case where the embankment 1 is newly constructed will be described with reference to FIG. When the embankment 1 is newly installed, the embankment material layers 16A, 16B and the like are formed by repeating the work of laying the embankment material one layer at a time from the base and rolling the embankment material.

The thickness D of one layer of the embankment material layers 16A and 16B is usually about 30 cm. Subsequently, as shown in FIG. 5A, the embankment material is laminated to a predetermined height, and then the capillary barrier layer 3 is provided on the embankment material layer 16B. The thickness D of the capillary barrier layer 3 is also the same as the thickness D of the other embankment material layers 16A and 16B. Then, on the back surface side of the capillary barrier layer 3, the embankment material layer 16C is provided by the embankment material.

Subsequently, as shown in FIG. 5B, a perforated drainage pipe 4 is installed on the capillary barrier layer 3. The perforated drainage pipe 4 is arranged so as to have a predetermined drainage gradient and the discharge port 41 is exposed to the inclined surface 11. Further, a plurality of perforated drainage pipes 4, ... Are arranged at intervals in the direction orthogonal to the paper surface of FIG.

Then, as shown in FIG. 5 (c), the embankment material is spread and leveled so as to bury the perforated drainage pipe 4, and the embankment material layer 16D is provided by rolling. The area around the inclined surface 11 of the embankment material layer 16D is the water retention area 5.

On the embankment material layer 16D, general embankment materials are repeatedly laminated again, and when the height at which the next drainage group 2 is provided is reached, the capillary barrier layer 3 is laid and the perforated drainage is performed in the same manner as described above. Install the pipe 4. These operations are repeated until the top 12 of the embankment 1 is reached. In this way, as shown in FIG. 3, an embankment structure in which the drainage group 2 is continuous in the width direction of the inclined surface 11 is constructed.

Next, with reference to FIG. 6, regarding a method of repairing the embankment structure for providing the drainage group 2A at intervals in the width direction of the inclined surface 11 as shown in FIG. 4 with respect to the existing embankment 1. explain. The embankment structure as shown in FIG. 4 can be constructed even in the case of a new construction, but since the description of the process is only a partial implementation of the above-mentioned construction method, detailed description thereof will be omitted.

First, as shown in FIG. 6A, excavation is partially performed from the inclined surface 11 of the embankment 1 toward the inside of the embankment. That is, an excavation portion 17 having a substantially right triangle shape in cross-sectional view is provided to expose the horizontal bottom surface 171.

As shown in FIG. 6B, a capillary barrier layer 3A is provided on the bottom surface 171. The thickness D of the capillary barrier layer 3A can be arbitrarily set. Subsequently, the perforated drainage pipe 4 is installed on the capillary barrier layer 3A. The perforated drainage pipe 4 is arranged so as to have a predetermined drainage gradient and the discharge port 41 is exposed to the inclined surface 11.

Then, as shown in FIG. 6 (c), the backfilling portion 6 is provided by filling the embankment material so as to bury the perforated drainage pipe 4. The lower part of the backfill portion 6 is the water retention area 5. By providing a partial excavation portion 17 with respect to the existing embankment 1 in this way, the drainage group portions 2A, ... As shown in FIG. 4, are spaced apart in the width direction of the inclined surface 11. It can be renovated to the embankment structure provided.

When the drainage group 2A is provided on the existing embankment 1, the perforated drainage pipe 4 is driven from the inclined surface 11 toward the inside of the embankment instead of first providing the excavation part 17, and the lower part thereof is dug. By substituting it with coarse grain soil, the step of providing the capillary barrier layer 3A can also be performed.

Next, the operation of the embankment structure, the method of constructing the embankment structure, and the method of repairing the embankment structure of the present embodiment will be described.
The embankment structure of the present embodiment configured in this way includes a capillary barrier layer 3 (3A) extending from the inclined surface 11 toward the inside of the embankment, and soil particles having a fine particle size provided in contact with the upper surface thereof (3A). A perforated surface 11 is provided with a discharge port 41 extending near the boundary between the water retention area 5 (5A) formed by the fine-grained soil), the capillary barrier layer 3 (3A), and the water retention area 5 (5A). It is equipped with a drainage pipe 4.

A plurality of drainage group portions 2 (2A) including the capillary barrier layer 3 (3A), the perforated drainage pipe 4 and the water retention area 5 (5A) are spaced apart from each other in the height direction of the inclined surface 11. Is provided.
When water infiltrates into the inclined surface 11 of such an embankment structure due to precipitation R, the vicinity of the boundary between the capillary barrier layer 3 (3A) and the water holding area 5 (5A) of each drainage group 2 (2A) has a degree of saturation. Becomes the locally increased water retention area C.

That is, the water retention area 5 (5A) above the capillary barrier layer 3 (3A) makes it easy for water to be discharged. Therefore, by arranging the perforated drainage pipe 4 in the water retention area 5 (5A), water can be quickly discharged to the outside of the embankment. Further, the seepage water that has reached the capillary barrier layer 3 (3A) is drained as it is from the inclined surface 11 side of the capillary barrier layer 3 (3A).

Therefore, even if a large amount of water permeates the inclined surface 11 in a short time due to heavy rain or the like, the infiltrated water is efficiently drained from the drainage group 2 (2A) when flowing down the inside of the embankment, and the inclined surface 11 It is possible to effectively prevent the occurrence of surface collapse and slope collapse in the vicinity.

If it is a new construction, such an embankment structure can be completed by sequentially providing a structure to be a drainage assembly portion 2 in the middle of the process of laminating the embankment material. Further, even when the existing embankment 1 is repaired, the drainage group 2 can be provided by continuously excavating the inclined surface 11 in the width direction.

Further, when the existing embankment 1 is to be repaired, a configuration that becomes the drainage group 2A can be easily provided by partially excavating the inclined surface 11 toward the inside of the embankment. Even if the drainage group 2A, ... Is provided discretely on the inclined surface 11, the inside of the embankment can be efficiently drained. be able to.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes to the extent that the gist of the present invention is not deviated are made in the present invention. Included in the invention.
For example, in the above-described embodiment, the configuration in which the water retention area 5 (5A) formed by the fine-grained soil is provided as the upper layer of the capillary barrier layer 3 (3A) formed by the gravel material has been described, but the present invention is limited to this. It suffices if the structure allows a relative difference in water permeability between the lower layer and the upper layer.

Further, in the above-described embodiment, the perforated drainage pipe 4 has been described as an example as the drainage route portion, but the present invention is not limited to this, and the water retained without affecting the development of the capillary barrier is placed outside the embankment. Any form of drainage route such as a rectangular parallelepiped-shaped or face plate-shaped filter material may be used as long as the drainage route can be discharged.

Further, in the above embodiment, the case where the capillary barrier layers 3 and 3A are formed of the same material from the inclined surface 11 toward the inside of the embankment has been described, but the present invention is not limited thereto. For example, the drainage group 2B as shown in FIG. 7 can be provided.

In the drainage group 2B shown in FIG. 7, the capillary barrier layer 3B is a fine-grained soil portion formed by a coarse-grained soil portion 31 formed of coarse-grained soil and soil particles having a finer particle size than the coarse-grained soil. It is composed of the embankment material part 32 of.

The coarse grain soil portion 31 and the embankment material portion 32 are alternately arranged from the inclined surface 11 toward the inside of the embankment. That is, the space between the coarse-grained soil portions 31 and 31 arranged at intervals toward the inside of the embankment is filled with the embankment material portion 32 formed by the embankment material constituting the embankment 1. Then, the gathering of the coarse-grained soil portions 31, 31 and the embankment material portions 32, 32 extending substantially horizontally from the inclined surface 11 toward the inside of the embankment forms the capillary barrier layer 3B.

1: Embankment 11: Inclined surface 17: Excavation part 171: Bottom surface 2, 2A: Drainage group part 3, 3A, 3B: Capillary barrier layer 31: Coarse grain soil part 32: Embankment material part (fine grain soil part)
4: Perforated drainage pipe (drainage route)
41: Discharge port 5, 5A: Water retention area 6: Backfilling part B1: Spacing B3: Spacing

Claims (9)

It is an embankment structure where an inclined surface is formed.
A capillary barrier layer formed inside the embankment with a predetermined thickness,
A water retention area provided on the capillary barrier layer having a higher water permeability in an unsaturated state than the capillary barrier layer,
It is provided with a drainage path portion that is stretched near the boundary between the capillary barrier layer and the water retention area, takes in water that has permeated the water retention area, and is provided with a discharge port on the inclined surface.
The embankment structure is characterized in that a plurality of the capillary barrier layer, the drainage path portion, and the drainage group portion including the water retention area are provided at intervals in the height direction of the inclined surface. The embankment structure according to claim 1, wherein the drainage assembly portion is continuously provided in the width direction of the inclined surface, and the drainage route portion is provided at intervals in the width direction. .. The embankment structure according to claim 1, wherein the drainage assembly portions are provided at intervals in the width direction of the inclined surface. The capillary barrier layer is inclined by alternately arranging coarse-grained soil portions formed of coarse-grained soil and fine-grained soil portions formed of soil particles having a finer particle size than the coarse-grained soil. The embankment structure according to any one of claims 1 to 3, wherein the structure is substantially horizontally extended from the surface toward the inside of the embankment. The embankment structure according to any one of claims 1 to 4, wherein the thickness of the capillary barrier layer is 20 cm to 50 cm. The embankment structure according to any one of claims 1 to 5, wherein the capillary barrier layer is formed of coarse-grained soil having a particle size of 20 mm to 150 mm. The embankment according to any one of claims 1 to 6, wherein the capillary barrier layer has a structure extending substantially horizontally from the inclined surface toward the inside of the embankment with a length of 2 m to 3 m. Construction. It is a method of constructing an embankment structure where an inclined surface is formed.
The process of laminating embankment materials and
The process of providing a capillary barrier layer by laying coarse-grained soil or drainage material inside the embankment with a predetermined thickness, and
A step of extending a drainage path portion on the capillary barrier layer so that a discharge port is provided on the inclined surface, and a step of extending the drainage path portion.
A step of providing a water retention area on the capillary barrier layer in which the water permeability in an unsaturated state is higher than that of the capillary barrier layer, and
A method for constructing an embankment structure, which comprises a step of repeatedly providing a drainage group having a capillary barrier layer, a drainage path portion, and a water retention area between the embankment material layer and the embankment material layer. .. It is a method of repairing the embankment structure where the existing inclined surface is formed.
The process of partially excavating the inclined surface toward the inside of the embankment,
A process of providing a capillary barrier layer by laying coarse-grained soil or drainage material with a predetermined thickness on the excavated bottom surface, and
A step of extending a drainage path portion on the capillary barrier layer so that a discharge port is provided on the inclined surface, and a step of extending the drainage path portion.
A method for repairing an embankment structure, which comprises a step of providing a water retention area having a water permeability higher than that of the capillary barrier layer in an unsaturated state on the capillary barrier layer and the drainage channel portion.

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